Production of cyclic acetals or ketals using liquid-phase acid catalysts

ABSTRACT

A liquid composition containing at least 2 mole % of water, at least 50 mole % of polyhydroxyl compounds, at least 3 mole % of cyclic compounds, and at least 0.01 mole % of a homogeneous acid catalyst. The mole percentages are based on the moles of all liquids in the composition. The liquid composition optionally contains up to 20 mole % of carbonyl compounds, based on the number of moles of the cyclic compounds. The cumulative amount of any other liquid ingredient in the liquid composition does not exceed 10 mole %. The cyclic compounds include cyclic acetals, cyclic ketals, or a combination thereof. The liquid composition is derived from a process for making cyclic compounds by feeding aldehyde or ketone compounds and polyhydroxyl compounds to a reaction vessel at a molar ratio of polyhydroxyl compounds to aldehyde or ketone compounds of at least 3:1, reacting these compounds in the presence of a homogeneous acid catalyst to generate a liquid phase homogeneous reaction mixture containing the acid catalyst without separating water from the reaction mixture as it is being formed in the reaction mixture, withdrawing the liquid phase homogeneous reaction mixture from the reaction vessel as a liquid product stream, and feeding the liquid reaction product stream to a distillation column to separate cyclic acetal or ketal compounds from unreacted polyhydroxyl compounds.

1. CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No. 13/168,374filed on Jun. 24, 2011, the disclosure of which is incorporated hereinby reference in its entirety.

2. FIELD OF THE INVENTION

The invention relates to the production of cyclic acetals or ketals athigh yields.

3. BACKGROUND OF THE INVENTION

Ether alcohols, such as 2-butoxyethanol, have important industrialfunctions in such products such as cleaning supplies and coatingmaterials. In the past, the manufacture of these products has been basedon a process relying on a reaction between an alcohol and ethyleneoxide. This conventional process has proven to be somewhat inefficient,in that it produces various undesirable byproducts along with the etheralcohols.

Monoether glycols can also be manufactured in a reaction betweenaliphatic aldehydes and ethylene glycol, instead of ethylene oxide,under acidic conditions in order to produce cyclic acetals. The acetalof ethylene glycol and butyraldehyde, for example, is described byHibbert and Timm (Hibbert, H.; Timm, J. A. J. Am. Chem. Soc. 1924,46(5), 1283-1290) and is achieved with a maximum yield of 50%. Thesecyclic acetals, or ketals when a ketone is substituted for the aldehyde,can then be subjected to hydrogenolysis in the presence of palladium andphosphoric acid catalysts. Such a process is described in U.S. Pat. No.4,484,009.

The reaction of the polyhydroxyl compounds with aldehydes or ketones isan equilibrium reaction with the acetal product and by-product water.Yield of acetal or ketal is reduced via hydrolysis of the acetal by theco-product water. Thus, it is desirable to remove water from thereaction system to increase yield of the acetal.

The separation of water from the reaction mixture has been difficultsince it often forms an azeotrope with the aldehyde reactants and withthe cyclic acetal products. Entrainers have been employed to removewater through azeotropic distillation. Sulzbacher and coworkers, forexample, describe removing the water by using benzene during thepreparation of a number of acetals of ethylene glycol (Sulzbacher, M.et. al. J. Am. Chem. Soc. 1948, 70(8), 2827-2828). The environmental andhealth impact of benzene is an obvious concern in this method.Dessicants such as calcium chloride (DE 419223; Brönsted and Grove J.Am. Chem. Soc. 1930, 52(4), 1394-1403.) may be employed in the reactionvessel to remove water as it is formed, but disposal of the generatedsolid waste is an economic and environmental concern.

Another method as described by Astle and coworkers, involves heating theglycol and aldehyde over an heterogeneous acidic resin and distillingout the acetal and water as they are formed (Astle, M. J. et al, Ind.Eng. Chem. 1954, 46(4), 787-791). This method generally had low yieldswith one example for the manufacture of 2-butoxyethanol reported ashaving a yield of about 92% using a molar ratio of ethylene glycol tobutyraldehyde of about 1.3:1. In these reactions, water was beingseparated from the reaction mixture in the flask as the water was beingformed, and upon completion, the reaction mixture in the flask wasfiltered and phase separated. The removal of water from the reactionmixture as it was being formed follows from the understanding that thereaction of the polyhydroxyl compounds with aldehydes is an equilibriumreaction with the acetal product and by-product water, and the yield ofacetal is reduced via hydrolysis of the acetal by the co-product wateror can be increased with the removal of water as it is formed.

One pot reaction systems have also been reported, that is, reacting analdehyde and a polyhydroxyl with hydrogen in the presence of a noblemetal catalyst directly to the desired ether alcohol. For example, U.S.Pat. No. 5,446,210 describes a process for the production of hydroxyether hydrocarbons in a one pot system by reacting a polyhydroxyl withan aldehyde and hydrogen in the presence of a noble metal catalyst wherethe molar ratio of polyhydroxyl to aldehyde compound ranges from 5:1 to1:5 is described, but with these molar ratios, the yield was low in therange of 35 to 50% when including the bis-types of by-products with lowselectivity to the mono-ether products.

US Publication No. 2010/0048940 also describes a one pot system in whicha polyhydroxyl and a aldehyde compound and hydrogen are reacted togetherin the presence of a hydrogenolysis catalyst to provide the polyhydroxylether, where the molar ratio of polyhydroxyl to aldehyde exceeds 5:1 toimprove selectivity and yield. An example of a two stage process inwhich the acetal compound was first synthesized and then subjected tohydrogenolysis was reported without describing the yield value of theacetal produced, although the yield to the 2-butoxyethanol byhydrogenolysis of the acetal was reported as having a selectivity ofabout 61%.

In U.S. Pat. No. 5,917,059 to BASF Aktiengesellschaft, the authorsgenerate cyclic acetals and ketals by reacting a molar excess ofaldehydes and ketones with polyhydroxyl compounds in the presence of anacid catalyst. The water is removed by continuously distilling unreactedaldehydes or ketone starting materials, thus co-distilling the formedwater in the water/aldehyde azeotrope, and further replacing thedistilled aldehyde or ketone with fresh aldehyde or ketone. Thealdehydes and ketones act not only as a reactant but also as a mediumfor transporting the water produced in the reaction. This methodrequires large excess of aldehyde (e.g. 4:1 molar ratio ofaldehyde:alcohol) to be successful.

Reactive distillation is employed in U.S. Pat. No. 6,015,875 and U.S.Pat. No. 7,534,922 B2 to generate low boiling acetals. The authors makeuse of heterogeneous acids in the packing of the column and feed lowboiling starting materials such as methanol, ethanol, formaldehyde, andacetaldehyde. The formed acetals are removed overhead above thedistillation reaction zone and the co-product water is removed below thedistillation reaction zone. This method limits the types of usablereactants to those producing materials that boil at a temperature lowerthan water.

As can be seen from the available literature, there exists a continuedneed to produce cyclic acetal or ketal compounds in high yield using asimple economic process.

4. BRIEF SUMMARY OF THE INVENTION

Cyclic acetals and ketals can now be produced in high yield in a simplemethod which does not require removal of water as it is generated.Contrary to the expectation that yields would be unacceptably low unlesswater is removed during its formation as a by-product, the process ofthe invention allows one to react all starting materials in the liquidphase in one reaction vessel to make a reaction mixture which is removedin the liquid phase and subsequently distilled to produce the desiredcyclic acetal or ketal in high yields.

There is now provided a continuous process for making a cyclic acetal orketal compounds comprising:

-   -   a. feeding a carbonyl composition comprising an aldehyde        compound, a ketone compound, or a combination thereof, and a        polyhydroxyl composition comprising a polyhydroxyl compound, to        a reaction vessel at a molar ratio of all polyhydroxyl compounds        to all carbonyl compounds fed to the reaction vessel of at least        3:1; and    -   b. in a reaction vessel, reacting the carbonyl composition with        the polyhydroxyl compound in the presence of a homogeneous acid        catalyst to generate a liquid phase homogeneous reaction mixture        in the reaction vessel comprising cyclic compounds, water, acid        catalyst, and unreacted polyhydroxyl compound; and    -   c. without separating water from the reaction mixture as it is        being formed in the reaction mixture, continuously withdrawing        the liquid phase homogeneous reaction mixture from the reaction        vessel as a liquid product stream; and    -   d. feeding the liquid reaction product stream directly or        indirectly to a distillation column to separate cyclic compounds        from unreacted polyhydroxyl compounds and withdrawing from the        distillation column an overhead product stream and a bottoms        stream, wherein the overhead product stream comprises cyclic        compounds, unreacted carbonyl compounds and water and is rich in        the concentration of cyclic compounds by moles relative to the        bottoms stream, and the bottoms stream comprises unreacted        polyhydroxyl compounds and acid catalyst and is rich in the        concentration of unreacted polyhydroxyl compounds by moles        relative to the overhead product stream;    -   wherein the selectivity to cyclic compounds in the overhead        product stream is at least 80%.    -   The yield of cyclic acetal or ketal compounds taken in an        overhead product stream can also be at least 80%.

In the process of the invention, one may also recycle to the reactionvessel at least a portion of unreacted polyhydroxyl compounds withdrawnfrom the distillation column in the bottoms stream. Reaction by-productsother than water may also be withdrawn from the bottoms stream toproduce a polyhydroxyl rich stream and an organic by-product richstream, following which at least a portion of the polyhydroxyl compoundsand acid catalyst in the polyhydroxyl rich stream can be recycled to thereaction vessel.

5. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a process flow diagram for the production of cyclic acetal orketal compounds in a reaction vessel followed by distillation,separation, and recycling a portion of polyhydroxyl compounds to thereaction vessel.

6. DETAILED DESCRIPTION OF THE INVENTION

There is now provided a continuous process for making cyclic compounds.By a cyclic compound is meant a compound having a ring structure thathas two oxygen atoms in the ring structure that are single bonded to thesame carbon atom in the ring structure. The cyclic compounds can becyclic acetal compounds or cyclic ketal compounds. The cyclic compoundsare made by feeding carbonyl compounds and a polyhydroxyl compositioncomprising a polyhydroxyl compound, to a reaction vessel at a molarratio of all polyhydroxyl compounds and all aldehyde or ketone compoundsfed to the reaction vessel of at least 3:1. By carbonyl compounds ismeant aldehyde compounds, ketone compounds (depending upon whether onedesires to make an acetal or ketal), or a mixture of the two.

The carbonyl composition fed to the reaction vessel contains one or moretypes of aldehyde or ketone compounds. Aldehyde compounds contain atleast one aldehyde functionality. The aldehyde and ketone compounds canbe represented by the Formula I:

in which R¹ and R² are independently hydrogen or a C₁-C₅₀ alkyl, C₂-C₅₀alkenyl, aryl-C₁-C₅₀ alkyl, aryl-C₂-C₅₀ alkenyl-, or C₃-C₁₂ cylcoalkyl,and wherein R¹ and R² are optionally connected through one or morecarbon atoms, and wherein the alkyl, alkenyl, aryl, and cycloalkylgroups of R¹ and R² are optionally saturated or unsaturated, andbranched or unbranched or substituted or unsubstituted with 1, 2, or 3groups comprising —OH, halogen, dialkylamino, C₁-C₆ alkyl, aldehyde,ketone, carboxylic acid, ester, ether, alkynyl, dialkylamide, anhydride,carbonate, epoxide, lactone, lactam, phosphine, silyl, thioether, thiol,aryl, phenol, or combinations thereof; and wherein when one of R¹ or R²is hydrogen, the compound will be an aldehyde and wherein when neitherR¹ and R² are hydrogen the compound is a ketone.

The aldehyde compound may have, if desired, at least one aldehydefunctional group wherein the aldehyde carbon atom is bonded to a (i)branched or unbranched C₁-C₉ alkyl group or (ii) an aryl or alicyclicgroup which is optionally substituted with a branched or unbranchedC₁-C₉ alkyl group.

Examples of an aldehyde compounds include, but are not limited to,benzaldehyde, acetaldehyde, propionaldehyde, butyraldehyde,isobutyraldehyde, pentaldehyde, 2-methylbutyraldehyde,3-methylbutyraldehyde, n-pentanal, isopentanal, hexyldehyde,heptaldehyde, 2-ethylhexyldehyde, octanal, nonanal, n-decanal,2-methylundecanal, lauryl aldehyde, myristyl aldehyde, cetyl aldehyde,stearyl aldehyde, behenyl aldehyde, glutaraldehyde, acrolein,crotonaldehyde, oleyl aldehyde, linoleyl aldehyde, linolenyl aldehyde,erucyl aldehyde, cinnamaldehyde, 1,3-cyclohexanedicarboxaldehyde,1,4-cyclohexanedicarboxaldehyde, and combinations thereof.

Examples of ketone compounds include, but are not limited to, acetone,methyl ethyl ketone (2-butanone), methyl propyl ketone (2-pentanone),methyl isopropyl ketone (3-methyl-2-butanone), methyl isobutyl ketone(4-methyl-2-pentanone), 2-hexanone, 2-heptanone(methyl amyl ketone),2-octanone, and acetophenone, and combinations thereof.

The polyhydroxyl composition fed to the reaction vessel contains one ormore types of polyhydroxyl compounds. Polyhydroxyl compounds have atleast two hydroxyl (—OH) functionalities. The polyhydroxyl compounds maycontain ether or ester linkages in the longest carbon chain.

Suitable polyhydroxyl compounds for the present invention include, butare not limited to ethylene glycol, 1,2-propanediol, 1,3-propanediol,1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,2-pentanediol,2,4-pentandiol, 2,2-dimethyl-1,3-propanediol, diethyleneglycol, andtriethyleneglycol, glycerin, trimethylolpropane, xylitol, arabitol, 1,2-or 1,3cyclopentanediol, 1,2- or 1,3-cyclohexanediol, and2,3-norbornanediol.

The cumulative amount of polyhydroxyl compounds and carbonyl compoundsfed to the reaction vessel are at a molar ratio of polyhydroxylcompounds relative to carbonyl compounds (aldehyde or ketone compounds)of at least 3:1, or at least 4:1, or more than 5:1, or at least 6:1, orat least 7:1, or at least 8:1, or at least 9:1, or at least 10:1, or atleast 13:1. There is no particular upper limit. It is economicallydesirable to limit the amount of polyhydroxyl compounds that need to beseparated and recycled balanced against the need to use an excesssufficient to enhance selectivity and yield to the desired cyclic acetalor ketal. Practically, a molar ratio of polyhydroxyl compounds tocarbonyl compounds does not need to be more than 30:1, or not more than20:1, and even not more than 15:1.

The molar ratio of polyhydroxyl compounds to carbonyl compounds isdetermined by the total amount fed to the reaction vessel. If a recyclestream of polyhydroxyl compounds is fed to the reaction vessel, thisquantity should be factored into the molar ratio.

The polyhydroxyl composition and the carbonyl compounds composition maybe fed as separate streams or as a combined stream into the reactionvessel. If viscosity variances between the two are sufficiently great,it is desirable to pre-mix at least a portion of the polyhydroxylcomposition with at least a portion of the carbonyl compounds toincrease the yield and improve the number of contact sites between thealdehyde or ketone functionalities and hydroxyl functionalities. Asshown in FIG. 1, a polyhydroxyl composition stream 1 and a carbonylcompound composition stream 2 are premixed in a mixing zone prior toentering reaction vessel through a reactant feed stream 3. It is alsopossible to feed the recycle stream 10 containing unreacted polyhydroxylcompounds and acid catalyst into the mixing zone to adequately mix anduniformly disperse or dissolve all the carbonyl compounds in thepolyhydroxyl composition, especially if the polyhydroxyl composition hasa significantly higher viscosity than the carbonyl composition.

Either or both the polyhydroxyl composition and the carbonyl compositionmay be pre-heated if the viscosity of either or both are too high toprovide satisfactory mixing or if either or both are solids at ambientconditions. The polyhydroxyl compounds and the carbonyl compounds shouldbe in the liquid state upon entry into the reaction vessel.

Polyhydroxyl compounds and the carbonyl compounds fed to the reactionvessel are reacted in the presence of a homogeneous acid catalyst.Examples of acid catalyst include Brønsted-Lowry acids. Acids that maybe used include hydrochloric acid, sulfuric acid, phosphoric acid,hydrofluoric acid, hydrobromic acid, hydroiodic acid, hydroperchloricacid, para-toluene sulfonic acid, and methyl sulfonic acid, triflicacid, trifluoro acetic acid, and tosic acid. These acids can be liquidor aqueous solutions and form a homogeneous phase in the liquid reactionmedium.

The acid catalyst may be fed to the reaction vessel separately orpremixed into one or both of the polyhydroxyl composition stream(s) 1,the carbonyl composition stream(s) 2, the recycle stream(s) 10, or thereactant stream 3 fed to the reaction vessel. The reaction vesselcontains a homogeneous reaction mixture, meaning that the acid catalystforms a homogeneous solution with other ingredients in the reactionvessel such that the contents of the reaction vessel are a homogeneousliquid phase reaction mixture, as distinguished from a reaction vesselthat contains a solid catalyst dispersed in a liquid reaction mixture ora fixed catalyst bed.

The reaction vessel is a vessel that accepts a feed or multiple feeds ofthe carbonyl compounds and the polyhydroxyl compounds before they arereacted with each other in the presence of the homogeneous catalyst. Thereaction vessel may also accept recycle feeds containing carbonyl orpolyhydroxyl compounds or homogeneous acid that have already been a partof a reaction mixture in the reaction vessel but are unreacted in thecase of the carbonyl or polyhydroxyl compounds. Since the homogeneouscatalyst is mobile, it is recognized that reactions may continue toproceed in the distillation vessel and downstream vessels from thedistillation column, and these vessels are distinct from the reactionvessel.

The reaction vessel is desirably liquid full and the reaction mixture inthe reaction vessel flows in the direction of the feed entry points tothe effluent locations. In a horizontal vessel, this can be a horizontalflow from left to right or right to left depending on the feed/effluentconfiguration. In a vertically oriented vessel, this can be from top tobottom or bottom to top. In one embodiment, the reaction mixture insidethe reaction vessel flows in an upward direction of bottom to top. Byhaving the feed entry points at or near the bottom of the reactionvessel and the effluent at the top of the reaction vessel, better mixingis obtained.

The reaction vessel can be contained in any suitable vessel. In oneembodiment, the reaction vessel is a pipe or tank having an L/D ratio ofmore than 1:1, or more than 2:1, or more than 3:1, or more than 4:1, ormore than 5:1, or more than 6:1, or more than 7:1, or more than 8:1, ormore than 9:1, or more than 10:1.

The reaction vessel may be mechanically agitated. Practically, thereaction vessel is not mechanically agitated. For example, a pipe can beused without mechanical agitation, although if desired the pipe maycontain weirs or baffles to provide turbulent flow induced agitation

The reaction can proceed well under atmospheric pressure and at elevatedpressure. The pressure within the reaction vessel can be at least 0.1atm, or at least 0.5 atm, or at least 1 atm, or at least 1.05 atm, or atleast 1.1 atm, or at least 1.5 atm, or at least 2 atm, or at least 3atm, or at least 4 atm. For most applications, the pressure does notneed to exceed 10 atm, or exceed 5 atm, or exceed 3 atm, or exceed 2atm.

Inside the reaction vessel, polyhydroxyl compounds react with carbonylcompounds to produce cyclic acetals or cyclic ketals or a mixturethereof, water, and by-products. The cyclic acetal, for purposes of thisdescription, is the desired principal product produced from the reactionof the starting aldehydes and starting polyhydroxyl compounds. Theprincipal product, the cyclic acetal, is the cyclic reaction product ofone mole of the starting aldehyde compound with one mole of the startingpolyhydroxyl compound releasing one mole of water. Examples ofby-products in reaction mixture to make cyclic acetals arealdehyde-aldehyde reaction products, polyhydroxyl-polyhydroxyl reactionproducts, the secondary reaction products between cyclic acetals withany other reactants or with itself, internal re-arrangement of thecyclic acetal ring and any further reaction products resulting from thering re-arrangement, or a combination thereof. Since a high molar excessof polyhydroxyl compound is used, unreacted polyhydroxyl compounds willalso be present in the reaction mixture. The reaction mixture may alsocontain unreacted aldehyde compounds.

The same applies to the production of cyclic ketals. The cyclic ketal,for purposes of this description, is the desired principal productproduced from the reaction of the starting ketones and startingpolyhydroxyl compounds. The principal product, the cyclic ketal, is thecyclic reaction product of one mole of the starting ketone compound withone mole of the starting polyhydroxyl compound releasing one mole ofwater. Examples of by-products in reaction mixture to make cyclic ketalsare ketone-ketone reaction products, polyhydroxyl-polyhydroxyl reactionproducts, the secondary reaction products between cyclic ketals with anyother reactants or with itself, internal re-arrangement of the cyclicketal ring and any further reaction products resulting from the ringre-arrangement, or a combination thereof. Since a high molar excess ofpolyhydroxyl compound is used, unreacted polyhydroxyl compounds willalso be present in the reaction mixture. The reaction mixture may alsocontain unreacted ketone compounds.

The yield of a product compound (not by-products or water), whether onedesires to determine the yield of cyclic compounds, an acetal compound,or a ketal compound, is determined by dividing the moles of productcompounds produced by the moles of reactant fed in the lowest molarquantity, multiplied by 100. For example, the yield of cyclic compoundsis determined by dividing the moles of cyclic compounds produced by themoles of corresponding aldehyde and/or ketone compounds fed, multipliedby 100. The yield of cyclic acetal compounds is determined by dividingthe moles of cyclic acetal compounds produced by the moles of aldehydecompounds fed, multiplied by 100. The yield of cyclic ketal compounds isdetermined by dividing the moles of cyclic ketal compounds produced bythe moles of ketone compounds fed, multiplied by 100.

Selectivity of cyclic compounds is determined by dividing the moles ofcyclic compounds produced by the moles of their respective aldehyde orketone compounds converted, multiplied by 100. Selectivity to the cyclicacetal is determined by dividing the moles of cyclic acetal compoundsproduced by the moles of aldehyde compounds converted, multiplied by100. Selectivity to the cyclic ketal is determined by dividing the molesof cyclic ketal compounds produced by the moles of ketone compoundsconverted, multiplied by 100.

Conversion to cyclic compounds is determined by dividing the moles ofcyclic compounds converted by the moles of the respective aldehyde orketone compounds fed, multiplied by 100. Conversion to cyclic acetals isdetermined by dividing the moles of cyclic acetal compounds converted bythe moles of aldehyde compounds fed, multiplied by 100. Conversion tocyclic ketals is determined by dividing the moles of cyclic ketalcompounds converted by the moles of ketone compounds fed, multiplied by100.

In the process of the invention, high yields of cyclic compounds areobtainable without the necessity of separating the by-product water fromthe reaction mixture as it is being formed in the reaction mixture. Eventhough the reaction is an equilibrium reaction with the presence ofwater having the capability to hydrolyze the acetal or ketal product andlower yield, the reaction of polyhydroxyl compounds in high molar excesswith aldehyde compounds in the presence of the acid keeps theselectivity and yield of cyclic acetal high. This has the advantage thatwater is not required to be removed by distillation or other means inthe reaction vessel as it is being formed in order to obtain highyields. Further, the reaction processing window is widened and notconstrained by the boiling point ranges of the reactants and reactionproducts and by-products.

The cyclic reaction products formed in the reaction mixture contain anacetal moiety or a ketal moiety or both. The cyclic compounds producedin the process of the invention have two oxygen atoms single bonded tothe same carbon atom in the ring structure. Suitable cyclic acetal andketal moieties include 1,3-dioxolane moieties and 1,3-dioxane moieties,although larger ring compounds having oxygen atoms in the 1,3 positionare also contemplated.

The cyclic compounds produced in the process of the invention thatincludes a cyclic acetal moiety or a cyclic ketal moiety may berepresented by the general Formula II:

-   -   wherein R¹, R², R³, and R⁴ are independently H; a branched or        un-branched C₁-C₅₀ alkyl, C₂-C₅₀ alkenyl, aryl-C₁-C₅₀ alkyl,        aryl-C₂-C₅₀ alkenyl-, C₃-C₁₂ cycloalkyl, or a C₃-C₅₀ carboxylate        ester; and wherein R¹ and R² may optionally be bonded to each        other through one or more carbon atoms, and wherein R¹, R², R³,        and R⁴ optionally containing 1, 2, or 3 oxygen atoms in the        alkyl or alkenyl group, and wherein the alkyl, alkenyl, aryl,        and cycloalkyl groups of R¹, R², R³, and R⁴ are optionally        substituted with 1, 2, or 3 groups independently selected from        —OH, halogen, dialkylamino, aldehyde, ketone, carboxylic acid,        ester, ether, alkynyl, dialkylamide, anhydride, carbonate,        epoxide, lactone, lactam, phosphine, silyl, thioether, thiol,        and phenol;    -   wherein any one or both of R³ and R⁴ are optionally        independently a hydroxyl, halogen, dialkylamino, amine,        aldehyde, ketone, carboxylic acid, ester, ether, alkynyl,        dialkylamide, anhydride, carbonate, epoxide, lactone, lactam,        phosphine, silyl, thioether, thiol, or phenol;    -   wherein R⁵ is branched or unbranched divalent alkyl or divalent        alkenyl group each having 1 to 20 carbon atoms and optionally        containing 1, 2, or 3 oxygen atoms in the alkyl or alkenyl group        and optionally substituted with —OH, halogen, dialkylamino,        aldehyde, ketone, carboxylic acid, ester, ether, alkynyl, aryl,        dialkylamide, anhydride, carbonate, epoxide, lactone, lactam,        phosphine, silyl, thioether, thiol, and phenol; and    -   wherein n is an integer selected from 0 or 1.

R¹, R², R³, and R⁴ may independently be H, or a branched or un-branchedC₁-C₆ alkyl group. Or, R¹, R², R³, and R⁴ may independently be H, or abranched or un-branched C₁-C₄ alkyl group. R¹ may be a branched orunbranched C₁-C₆ alkyl group while R² is a hydrogen atom to provide acyclic acetal.

R⁵ may be a branched or unbranched divalent alkyl group having 1 to 6,or 1 to 4, or 1 to 3, or 1 to 2 carbon atoms.

Particularly useful cyclic acetals for this invention leading to usefulmaterials of commerce include 1,3-dioxolanes having R1 being an alkylgroup that can lead to “E-series” type solvents. Likewise,1,3-dioxolanes having R1 being an alkyl group and R3 being a methylgroup can lead to “P-series” type solvents.

Examples of cyclic acetals include 2-propyl-1,3-dioxolane,2-propyl-1,3-dioxane, 2-ethyl-1,3-dioxolane, 2-ethyl-1,3-dioxane,2-methyl-1,3-dioxolane, 2-methyl-1,3-dixoane,2-propyl-4-methyl-1,3-dioxane, 5,5-dimethyl-2-propyl-1,3-dioxane,5,5-dimethyl-2-ethyl-1,3-dioxane, 2-ethyl-1,3-dioxepane,2-ethyl-1,3,6-trioxocane, 4-methanol-2-propyl-1,3-dioxolane, or4-methanol-2-propyl-1,3-dioxane, 4-methanol-2-propyl-1,3-dioxolane, and2-propyl-1,3-dioxane-4-ol.

Examples of cyclic ketals include 2,2-dimethyl-1,3-dioxolane,2,2-dimethyl-1,3-dioxane, 2,2,4-trimethyl-1,3-dioxolane,2,2-dimethyl-1,3-dioxepane, 4-methanol-2,2-dimethyl-1,3-dioxane,2,2-dimethyl-1,3-dioxan-4-ol, 2,2-dimethyl-1,3-6-trioxocane,2-isopropyl-2-methyl-1,3-dioxolane, 2-isopropyl-2-methyl-1,3-dioxane,2-isopropyl-2,4-dimethyl-1,3-dioxolane,2-isopropyl-2-methyl-1,3-dioxepane,4-methanol-2-isopropyl-2-methyl-1,3-dioxane,2-isopropyl-2-methyl-1,3-dioxan-4-ol,2-isopropyl-2-methyl-1,3-6-trioxocane, 2-methyl-2-pentyl-1,3-dioxolane,2-methyl-2-pentyl-1,3-dioxane, 2,4-dimethyl-2-pentyl-1,3-dioxolane,2-methyl-2-pentyl-1,3-dioxepane,2-methyl-2-pentyl-4-methanol-1,3-dioxolane,2-methyl-2-pentyl-1,3-dioxan-4-ol, 2-methyl-2-pentyl-1,3-6-trioxocane,

The reaction mixture is not treated to separate water from the reactionmixture prior to withdrawing the reaction mixture from the reactionvessel. The reaction vessel is liquid full with the liquid in thereaction vessel being well mixed or proceeding in plug flow. Thereaction temperature is no particularly limited. The reaction conditionsinside the reaction vessel desirably keep the reaction mixture in aliquid state and are not set to exceed the boiling point of the mixtureunder the reaction conditions. Suitable reaction temperatures are atleast −15° C., or at least 0° C., or at least 15° C., or at least 25°C., or at least 30° C., or at least 40° C., and desirably less than 110°C., up to 90° C., or up to 70° C., or up to 50° C.

The reaction mixture is withdrawn from the reaction vessel as a liquidproduct stream line 4 as illustrated in FIG. 1. The product stream isconsidered a liquid product stream if water, cyclic compounds, andpolyhydroxyl compounds are present in the product stream as a liquid andhave not been subjected to temperatures above the boiling point of themixture in the reaction vessel under reaction vessel conditions.

The liquid product stream removed from the reaction vessel is also aunique composition. There is now provided a liquid compositioncomprising water, polyhydroxyl compounds, and cyclic compounds, each inthe following mole percentages based on the moles of all liquids in thecomposition:

-   -   a. water: at least 2 mole %, or at least 3 mole %, or at least 6        mole %, or at least 8 mole %, or at least 10 mole %, and up to        35 mole %, or up to 25 mole %, or up to 20 mole %, or up to 15        mole %;    -   b. polyhydroxyl compounds: at least 50 mole %, or at least 60        mole %, or at least 65 mole %, or at least 70 mole %, and up to        95 mole %, or up to 90 mole %, or up to 85 mole %;    -   c. cyclic compounds: at least 2 mole %, or at least 3 mole %, or        at least 5 mole %, or at least 7 mole %, and up to 35 mole %, or        up to 25 mole %, or up to 20 mole %, or up to 15 mole %;    -   d. acid catalyst: at least 0.01 mole %, or at least 0.1 mole %,        or at least 0.2 mole %, or at least 0.25 mole % and up to 5 mole        % or up to 4 mole % or up to 3 mole % or up to 2 mole % or up to        1 mole % or up to 0.75 mole %;        wherein the liquid composition optionally contains carbonyl        compounds which, if present, do not exceed 20% of the number of        moles of cyclic compounds, and wherein the cumulative amount of        all liquid ingredient in the liquid composition other than a),        b), c), and carbonyl compounds, if present, does not exceed 10        mole %, and the cyclic compounds comprise cyclic acetals, cyclic        ketals, or a combination thereof.

The liquid composition optionally contains carbonyl compounds (i.e.aldehyde and/or ketone compounds) which, if present, do not exceed acumulative amount of 15%, or do not exceed 12%, of the number of molesof cyclic compounds, and wherein the amount of any other liquidingredient in the liquid composition does not exceed 8 mole %, or doesnot exceed 6 mole %.

The cyclic compound in the liquid product stream may be a cyclic acetalor a cyclic ketal. The liquid product stream line 4 is fed directly orindirectly to a distillation column to separate the cyclic compounds andwater and unreacted carbonyl compounds as one or more overhead productstreams and unreacted polyhydroxyl compounds and acid catalyst as one ormore bottoms streams. The overhead product stream(s) may be a singleoverhead product stream as shown in line 5 of FIG. 1 or multipleoverhead product streams. The overhead product stream(s) exiting thedistillation column is desirably a vapor stream(s). At least a portionof the condensable compounds in these vapor streams are desirablycondensed for use as reflux and/or to isolate useful cyclic acetalproducts and thereafter purify the concentration of the liquid cyclicacetal products through conventional concentration and/or separationtechniques.

As shown in FIG. 1, the distillation column has an overhead productstream line 5, which is desirably a vapor when exiting the distillationcolumn and may be condensed if desired. The overhead product streamexiting the column is rich in the concentration by weight of cycliccompounds relative to the concentration by weight of cyclic compoundspresent in bottoms stream, or in other words, the quantity of cycliccompounds in the overhead product stream is greater than the quantity ofcyclic compounds withdrawn from the distillation column as a bottomsstream. It is preferred that the same holds true for water in that wateris present in the overhead product stream and the overhead productstream is rich in concentration relative to the concentration in thebottoms stream. By rich is meant a higher concentration (in mole %) inone stream than the concentration of the same ingredient in thecomparative stream, and that the concentration is measured against allcompounds which condense at 0° C. or higher (condensables). Likewise,the overhead product stream is rich in the molar concentration ofunreacted carbonyl compounds relative to the concentration of unreactedcarbonyl compounds in the bottoms stream.

While the overhead product stream may contain unreacted polyhydroxylcompounds, the overhead product stream is depleted (concentration bymoles is less) in the quantity of this ingredient relative to itsquantity (concentration by moles) present in the bottoms stream. Thus,the bottoms stream is enriched in the number of unreacted polyhydroxylcompounds relative to the number present in the overhead product stream.The bottoms stream exits the distillation column as a liquid stream. Thebottoms stream may also contain by-products other than water. It isdesirable that if by-products are present, that the quantity present inthe bottoms stream is greater than the quantity in the overhead productstream.

The number of theoretical stages or plates in the distillation columncan be from about 5 to about 100, or about 10-30 plates.

The overhead product stream can be subjected to condensation in acondenser. The condensate is collected in a receiver or reflux drum andoptionally separated by any conventional means, such as a decanter. Theupper organic rich phase of the condensate in the receiver is withdrawnand recovered as product and can be further processed and purified toisolate a purified cyclic compound stream. The lower phase of thereceiver is water rich, withdrawn from the receiver, and sent to a watertreatment facility or further processed. Instead of a condenser, theoverhead product stream can be fed to a second distillation column toseparate water and unreacted carbonyl compounds from the desired cycliccompounds.

Table 1 below illustrates the mole % ranges (concentration ranges) foreach ingredient in the overhead product stream removed from thedistillation column train and after decanting (including the combinationof the aqueous and organic phases), wherein the stated mole % is basedon the weight of all ingredients within the overhead stream:

TABLE 1 Ingredient Mole % Mole % Mole % Water  30-50%   44-50%   47-49%Unreacted 0.1-20%    2-8%    4-6% Carbonyl Compounds By-Products   0-10%  0-5.0% 1.0-2.0% Cyclic Compounds  30-50%   40-50% 43.0-44.0% (acetals, ketals, or a combination) Polyhydroxyl   0-20%   0-4.0%0.5-1.0% Compounds

The values in Table 1 above also apply to the mole % ranges for eachingredient in the overhead product stream, wherein the stated molepercentages are based on the cumulative moles of all fresh feedsentering the process.

The product stream exiting the reaction vessel may optionally besubjected to one or more process steps prior to entering thedistillation column.

The bottoms stream 6 can be subjected to further process steps ifdesired. For example, the unreacted polyhydroxyl compounds and liquidacid catalyst present in the bottoms stream may be separated from thebottoms stream by any conventional separation technique. One suchadvantageous technique is feeding the bottoms stream to a settling tankand phase separating the unreacted polyhydroxyl compounds from theby-products. The by-products advantageously phase separate as a toplayer and can be decanted and removed from the bottom polyhydroxyl/acidcatalyst layer as a by-product stream 7 while the bottompolyhydroxyl/acid catalyst layer can be removed at a location below theby-product layer such as depicted in streams 9 and 10. Alternatively,the bottoms stream may be subjected to an extraction separationtechnique whereby a hydrocarbon extractant acting as a solvent for themore hydrophobic by-products is mixed with the bottoms stream to assistin the separation of the by-products stream. For example, organicsolvents may be used in the extraction of byproducts and introduced intoan extraction zone through stream 8. Suitable solvents include liquidhydrocarbons with four carbons to more than twenty carbons, saturatedand unsaturated, with or without cyclic structures, aliphatic and cyclicethers, esters, fatty acids, halogenated hydrocarbons, aliphaticnitriles, and aliphatic and aromatic amines. Specific examples oforganic solvents include heptane, octane, and nonane.

Often the polyhydroxyl compounds and the acid catalyst are separatedfrom the bottoms stream, at least a portion can be recycled back to thereaction vessel. As shown in FIG. 1, stream 10, a portion or all of thepolyhydroxyl compounds and acid catalyst separated from the bottomsstream and exiting the mixer/settler vessel are returned to a mixingzone feeding the reaction vessel. It is desirable to feed the recyclestream 10 to the mixing zone if a mixing zone is present to uniformlydisperse the carbonyl compounds in the polyhydroxyl composition. Aportion of the polyhydroxyl compounds and acid catalyst separated fromthe bottoms stream may be purged through stream 9 and further processedto purify and re-use the purge stream.

The process of the invention is capable of producing a cyclic compoundyield of at least 80%, or at least 84%, or at least 85%, or at least86%, or at least 88%, or at least 89%, and up to 100%, or up to 98%, orup to 95%, or up to 90% based on the amount of aldehyde compounds fed tothe reaction vessel. The yield can be conveniently determined bymeasuring the production of cyclic compounds in the overhead productstream removed from the distillation column.

It is desirable to convert at least 80%, or at least 84%, or at least84%, or at least 86%, or at least 88%, and up to 100%, or up to 98%, orup to 95%, or up to 93% of the aldehyde or ketone compounds.

The selectivity to the cyclic compounds can be at least 90%, or at least91%, or at least 92%, or at least 93%, or at least 94%, or at least 95%,or at least 96%, or at least 97%, or at least 98%, and up to 100%, or upto 99.5%, or up to 99%.

The process of the invention may be run in a batch mode, asemi-continuous mode, or a continuous mode. In a continuous mode and ina steady state operation, the process of the invention has a capacity ofproducing at least 70 metric tons/yr of cyclic compounds, or at least85, or at least 90, or at least 110 metric tons/yr.

The cyclic compounds in the separated cyclic compound stream can beconverted through hydrogenolysis to provide the corresponding etheralcohol solvents. For example, the following cyclic acetals2-propyl-1,3-dioxane, 2-ethyl-1,3-dioxolane, 2-ethyl-1,3-dioxane,2-methyl-1,3-dioxane, 5,5-dimethyl-2-propyl-1,3-dioxane,2-ethyl-1,3-dioxepane, 2-ethyl-1,3,6-trioxocane,4-methanol-2-propyl-1,3-dioxolane, or 2-propyl-1,3-dioxane-4-ol. aresuitable to make their respective solvents ethylene glycol monobutylether, 3-butoxy-1-propanol, ethylene glycol monopropyl ether,3-propoxy-1-propanol, ethylene glycol monoethyl ether,3-ethoxy-1-propanol, 3-butoxy-2,2-dimethyl-1-propanol,4-propoxy-1-butanol, and diethylene glycol monobutyl ether,3-butoxy-1,2-propanediol, and 2-butoxy-1,3-propanediol throughhydrogenolysis.

EXAMPLES

The following apparatus was used. A glass, jacketed vessel was used asthe reactor. It was maintained as liquid full by using an up-floworientation. A distillation column was also used. The distillationcolumn had two sections each being 1″ vacuum-jacketed glass columnsfilled with 0.24″ Pro-Pak distillation random packing. The upper sectionhad 15″ of packing, while the lower section had 30″ of packing. Thebottom reboiler was a 1-liter glass, hot-oil jacketed vessel attached tothe bottom of the lower column section. The top of the upper section wasconnected to a glass, jacketed, reflux splitter with a magneticswing-arm controller and a glass, jacketed condenser. The attached venthose was connected to an ice trap, pressure controller, and vacuum pump.Teflon tubing was used to connect equipment. The base of the columnreboiler was connected by tubing to a positive displacement pump.

The tubing from the discharge of this pump was connected to a separationzone, which was comprised of a mixer and settler. A glass feed vesselcontained a solvent. This solvent feed vessel was connected to apositive displacement pump. The tubing from this pump and the tubingfrom column bottom pump are connected together. This combined stream wasconnected to a mixer. The mixer was a glass, 30-ml vessel maintainedliquid-full which contained a magnetically-driven stirrer. The productstream from the mixer was connected to a 120-ml glass, jacketed vessel,which was a settler. This vessel had two exit ports, one on the top andone on the bottom. During operations, it was maintained liquid full. Itsjacket temperature set point was maintained at 90° C. The top port wasconnected to another positive displacement pump capable of removingmaterial enriched in solvent and byproduct. The bottom port wasconnected by tubing to feed-material pumps described below.

Glass feed vessels were used which contained aldehyde feed material andpolyol feed material, separately. Each was connected by tubing to apositive displacement pump. Tubing from these two feed-material pumpsand tubing from the mixer/settler were connected together. The combinedstream was connected to a glass, 30-ml liquid-full vessel whichcontained a magnetically-driven stirrer. This mixed stream was connectedto be bottom of the reactor vessel, completing the liquid circuit. Aprocess control system was utilized to monitor temperatures and pumpflow rates, and to control the distillation column reflux splitter,using a column temperature setpoint. In each example, n-butyraldehydewas used as the carbonyl compound at a feed rate of 1 ml/min, ethyleneglycol was used as the polyhydroxyl compound at a feed rate of 1 ml/min,and the feed rate of unconverted recycled material was 8 ml/min. Liquidacid catalyst was initially charged yet was not added during theexperiments.

Example 1 Phosphoric Acid, 40° C., Octane Solvent

1.8 g of phosphoric acid was added to 400 g of ethylene glycol, and thesolution was charged into the base of the distillation column. Thereactor jacket oil-bath temperature was set to 40° C. Octane, used asthe mixer/settler solvent, was added continuously, intermittently intothe mixer, and an octane stream enriched in reaction byproducts wasremoved from the settler. The process ran continuously for 25 hours. Theoverall conversion, selectivity, and yield to the production of2-propyl-1,3-dioxolane were high: 91.7%, 98.5%, and 90.3%, respectively.

Example 2 Phosphoric Acid, 22° C., Octane Solvent

The process described in Example 1, continued to operate, but thereactor jacket oil-bath temperature was set to room temperature, 22° C.The only catalyst in the process was what remained from Example 1. Theprocess ran continuously for 24 hours. The overall conversion,selectivity, and yield to the production of 2-propyl-1,3-dioxolane werehigh: 86.8%, 99.3%, and 86.2%, respectively.

Example 3 Phosphoric Acid, 40° C., Heptane Solvent

The process described in Example 2, continued to operate, but thereactor jacket oil-bath temperature was set to 40° C. The only catalystin the process was what remained from Example 2. In place of octane,heptane was used as the mixer/settler solvent. The process rancontinuously for 53 hours. Since the catalyst was re-used from theprevious two examples, the accumulated catalyst operating time was 102hours. The conversion data showed no decrease, indicating no loss incatalyst activity. The overall conversion, selectivity, and yield to theproduction of 2-propyl-1,3-dioxolane were high: 91.0%, 99.6%, and 90.6%,respectively.

What we claim is:
 1. A liquid composition comprising: a) at least 2 mole% of water; b) at least 50 mole % of polyhydroxyl compounds; c) at least3 mole % of cyclic compounds; and d) at least 0.01 mole % of ahomogeneous acid catalyst; wherein the mole percentages are based on themoles of all liquids in the composition, wherein the liquid compositionoptionally contains carbonyl compounds which, if present, do not exceed20% of the number of moles of the cyclic compounds, wherein thecumulative amount of any other liquid ingredient in the liquidcomposition does not exceed 10 mole %, and wherein the cyclic compoundscomprise cyclic acetals, cyclic ketals, or a combination thereof.
 2. Theliquid composition of claim 1, which comprises: a) 3 to 25 mole % ofwater; b) 50 to 90 mole % of polyhydroxyl compounds; c) 3 to 25 mole %of cyclic compounds; and d) 0.02 to 5 mole % of a homogeneous acidcatalyst.
 3. The liquid composition of claim 2, which comprises: a) 8 to25 mole % of water; b) 50 to 85 mole % of polyhydroxyl compounds; and c)7 to 25 mole % of cyclic compounds.